Its possible that Delsine could be Cole's unknown brother. In infamous 2 Cole mentions that he had a little brother that he hasnt spoken too in a while. The game is called Infamous Second Son so it could mean that its the second son in Cole's family because Cole himself is the first. Seeing as he is from Cole's family it would make sense that he has the conduit gene. The only thing that goes against this theory is his last name but it could mean that they had different fathers. Let me know what you guys think.
I'm closing this thread. This has already been discussed several times on several different forums. We don't need another one. Plus it's already been confirmed by Sucker Punch that Delsin has no blood relation to Cole.